var p1 = new Promise((resolve) => {
  resolve(1)
}).then(() => {
  console.log('xxxxx')
}).then(() => {
  console.log('yyyyy')
})

var p2 = new Promise((resolve) => {
  resolve(1)
}).then(() => {
  console.log('xxxxx')
}).then((res) => {
  console.log('yyyyy')
})


Promise.resolve().then(() => {
  console.log('xxxxx')
})
